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authorChristoph Hellwig <hch@lst.de>2011-07-08 14:34:42 +0200
committerChristoph Hellwig <hch@lst.de>2011-07-08 14:34:42 +0200
commit7a249cf83da1813cfa71cfe1e265b40045eceb47 (patch)
tree0c665aad7d32614f7eaa5a11c1b534c8fb5037d3 /fs/xfs
parent33b8f7c2479dfcbc5c27174e44b5f659d9f33c70 (diff)
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xfs: fix filesystsem freeze race in xfs_trans_alloc
As pointed out by Jan xfs_trans_alloc can race with a concurrent filesystem freeze when it sleeps during the memory allocation. Fix this by moving the wait_for_freeze call after the memory allocation. This means moving the freeze into the low-level _xfs_trans_alloc helper, which thus grows a new argument. Also fix up some comments in that area while at it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Alex Elder <aelder@sgi.com> Reviewed-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_fsops.c2
-rw-r--r--fs/xfs/xfs_iomap.c3
-rw-r--r--fs/xfs/xfs_mount.c14
-rw-r--r--fs/xfs/xfs_trans.c27
-rw-r--r--fs/xfs/xfs_trans.h10
5 files changed, 27 insertions, 29 deletions
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 9153d2c77caf..b7c492d293b5 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -626,7 +626,7 @@ xfs_fs_log_dummy(
xfs_trans_t *tp;
int error;
- tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
+ tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP, false);
error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
XFS_DEFAULT_LOG_COUNT);
if (error) {
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 091d82b94c4d..982b71108f33 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -688,8 +688,7 @@ xfs_iomap_write_unwritten(
* the same inode that we complete here and might deadlock
* on the iolock.
*/
- xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
- tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
+ tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS, true);
tp->t_flags |= XFS_TRANS_RESERVE;
error = xfs_trans_reserve(tp, resblks,
XFS_WRITE_LOG_RES(mp), 0,
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index b49b82363d20..63659ee316bd 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1566,15 +1566,9 @@ xfs_fs_writable(xfs_mount_t *mp)
}
/*
- * xfs_log_sbcount
- *
* Called either periodically to keep the on disk superblock values
* roughly up to date or from unmount to make sure the values are
* correct on a clean unmount.
- *
- * Note this code can be called during the process of freezing, so
- * we may need to use the transaction allocator which does not not
- * block when the transaction subsystem is in its frozen state.
*/
int
xfs_log_sbcount(
@@ -1596,7 +1590,13 @@ xfs_log_sbcount(
if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
return 0;
- tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP);
+ /*
+ * We can be called during the process of freezing, so make sure
+ * we go ahead even if the frozen for new transactions. We will
+ * always use a sync transaction in the freeze path to make sure
+ * the transaction has completed by the time we return.
+ */
+ tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP, false);
error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
XFS_DEFAULT_LOG_COUNT);
if (error) {
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index c83f63b33aae..2837220ea5cf 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -566,31 +566,24 @@ xfs_trans_init(
/*
* This routine is called to allocate a transaction structure.
+ *
* The type parameter indicates the type of the transaction. These
* are enumerated in xfs_trans.h.
- *
- * Dynamically allocate the transaction structure from the transaction
- * zone, initialize it, and return it to the caller.
*/
-xfs_trans_t *
-xfs_trans_alloc(
- xfs_mount_t *mp,
- uint type)
-{
- xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
- return _xfs_trans_alloc(mp, type, KM_SLEEP);
-}
-
-xfs_trans_t *
+struct xfs_trans *
_xfs_trans_alloc(
- xfs_mount_t *mp,
- uint type,
- uint memflags)
+ struct xfs_mount *mp,
+ uint type,
+ uint memflags,
+ bool wait_for_freeze)
{
- xfs_trans_t *tp;
+ struct xfs_trans *tp;
atomic_inc(&mp->m_active_trans);
+ if (wait_for_freeze)
+ xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
+
tp = kmem_zone_zalloc(xfs_trans_zone, memflags);
tp->t_magic = XFS_TRANS_MAGIC;
tp->t_type = type;
diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index 06a9759b6352..4e78432ce143 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -447,8 +447,14 @@ typedef struct xfs_trans {
/*
* XFS transaction mechanism exported interfaces.
*/
-xfs_trans_t *xfs_trans_alloc(struct xfs_mount *, uint);
-xfs_trans_t *_xfs_trans_alloc(struct xfs_mount *, uint, uint);
+xfs_trans_t *_xfs_trans_alloc(struct xfs_mount *, uint, uint, bool);
+
+static inline struct xfs_trans *
+xfs_trans_alloc(struct xfs_mount *mp, uint type)
+{
+ return _xfs_trans_alloc(mp, type, KM_SLEEP, true);
+}
+
xfs_trans_t *xfs_trans_dup(xfs_trans_t *);
int xfs_trans_reserve(xfs_trans_t *, uint, uint, uint,
uint, uint);